This invention relates generally to retaining walls. More particularly, the present invention relates to manufactured blocks that are used to construct mortarless retaining walls. Retaining walls can be both functional and decorative and range from small gardening applications to large-scale construction. Such walls are typically used to maximize horizontal surface areas by providing lateral support between differing ground levels, and reduce the possibility of erosion and slumping. They may be constructed of a variety of materials and shapes. Some have been constructed of wood timbers, others of rock in a natural form (such as limestone). Still others have been constructed of manufactured aggregate or concrete blocks.
Constructing a fit and true retaining wall can be a more labor intensive and exacting endeavor than one would believe. In addition to laying a level first course, the builder must take pains to ensure that each subsequent course is level. Otherwise, an error made in positioning a block in a lower course may become magnified as successive courses are stacked thereabove and become readily apparent to the human eye. This is especially true of mortarless wall constructions because there is no way to effectively compensate for irregularities and discontinuities, as opposed to block and mortar construction.
Present mortarless wall building methods usually include laying a course of blocks, filling the space behind the course with fill material, packing the fill material, and carefully removing extraneous fill material from the top of each completed course prior to the addition of the next course. This fill material usually consists of small stones or similar material and is preferred because it provides a path for moisture to follow and relieves water pressure that may build up behind a wall. It is also preferred because of its ability to reduce water borne material from seeping between the joints of the blocks due to inclement weather. The final step of removing the extraneous fill material is time consuming but necessary to ensure the next course of blocks lies flat in intimate contact on the lower course.
One particular problem the prior art has failed to overcome, is developing a retaining wall block configured to minimize or prevent unintended discontinuities and irregularities caused by blocks being stacked on extraneous fill material, dirt, and debris that is often present on the upper surface of the lower course of blocks.
For example, some larger blocks incorporate through-holes that extend from their bottom surface to their top surfaces. These through-holes are intended to reduce the amount of material required to form the block, thereby reducing its cost and weight, and they also create space into which fill material may be introduced once a course is finished. At first blush it would appear that, because the presence of through-holes reduces the surface area of the top and bottom of the block, they would also serve to decrease the area of possible interference by small stones and debris between courses. However, the mere presence of through-holes ensures the chances that some of the fill material dumped therein will spill over onto the remaining upper surfaces. Thus, through-holes actually exacerbate, rather than alleviate the problem.
Smaller blocks, on the other hand, cannot easily incorporate through-holes without jeopardizing their structural integrity, and this inability of smaller blocks to accommodate through-holes creates other problems. Fabricating a solid block out of material such as concrete may often result in a block which may weigh as much as or more than a larger block that includes through-holes. And, working with such blocks may be more difficult than working with larger blocks with through-holes. That is, the absence of through-holes or interruptions in the side walls makes it difficult to grasp and lift these blocks. This becomes an important consideration in light of the number of blocks that must be lifted and set in place during the construction of even a relatively small retaining wall.
There is a need for a retaining wall block which may accommodate debris between courses without adversely affecting the overall structure and aesthetics of the resulting wall. There is also a need for a small retaining wall block that has a reduced unit weight due to the absence of block material in an area that will not adversely affect the strength of the block or its appearance. And, there is a need for a small retaining wall block that is relatively easy to grasp and pick up off of a stack of similar blocks.